Ford TW20 brake problems.

[Lsmith80]

Hello, this is my first post, so please be gentle...
Currently I have a TW 20 causing me to show that I have emotions. The foot brake system is not holding fluid (mineral) and the problem originated from the master cylinder end, i.e, the rubber boot had perished on top of the cylinder, allowing muck in. That pair of cylinders has been re-lined now, so fairly confident that part of system is good. The muck made its way down of course, to the slave cylinder on one side, so I cleaned the piston and replaced the seals. That side is fine now. The other side is not holding fluid now though, so I took that trumpet off yesterday and did the same, but not sucessfully.
The questions:
Can the slave cylinder seals be checked for a successful seal, prior to putting the trumpet back?
Can the seals be put in wrong?

I'd be grateful if anyone can throw some light on the subject please.

 

[Flatlander]

When you say trumpet I assume you’ve pulled the half shaft housing off the diff. firstly if I’d have gone to the trouble of doing the cylinders I would have changed out the complete thing. brake fluid is hydroscopic so would adsorb moisture from the air. Likely those cylinders are pitted and although new seals won’t last as long as you hope. not familiar with the brake system on a TW but patching this type of breakdown isn’t one I’d cheap out on. They will fail when you need them the most. Always enough time and money to do it right the second time.

 

[Lsmith80]

Yes, the master cylinder/reservoir end is good now, it was pitted and has now been re-lined. The other end of the brake system seems to be the problem though.

 

[Flatlander]

If it’s pitted on one end it’s likely pitted the other.

 

[tw15]

Use lhm mineral fluid not dot4 on tw15 the piston just has big seals around it .

 

[forblue]

Brake fluid is not hydroscopic on tw as it's not automotive type. did you lubricate seal faces before refitting .

 

[Lsmith80]

Yes, lubed the seals with some brake fluid and gently tapped the piston/slave back in.
It's coming to bits again today and will see if the seals are ok still.

 

[Cowabunga]

Yes, lubed the seals with some brake fluid and gently tapped the piston/slave back in.
It's coming to bits again today and will see if the seals are ok still.

What sort of brake fluid did you use? That is quite critical. Are you using Dot4 or LHM hydraulic oil?

 

[Lsmith80]

It's a fluorescent green mineral fluid from New Holland.

 

[Nearly]

It's a fluorescent green mineral fluid from New Holland.

LHM then.

 

[Cowabunga]

It's a fluorescent green mineral fluid from New Holland.

In which case ‘LHM’ will be printed very large on the bottle. I think it is the correct fluid to use in TW brakes but you had better check the operator’s manual in case. The two fluids are incompatible. They do not mix well and the wrong one will cause seals to fail.
Is it possible that someone has topped the reservoir up with the wrong fluid in the relatively recent past?

 

[Lsmith80]

It is LHM fluid and that's right for those brakes according to the book. It's never had any other fluid since I've had the tractor and the whole system will be clear of any other type put in it, from all the flushing it's had with me.
The pic shows a very small bit of pitting (which I think is out of the sealed area just). I don't believe this is the problem, because of the speed of the leak as well as the area it's in...I am now thinking that I have possibly been sent the wrong seal, especially the small one, so I've ordered some more from a different dealer and will try again.

 

[Happy hillbily]

Yes, the master cylinder/reservoir end is good now, it was pitted and has now been re-lined. The other end of the brake system seems to be the problem though.

Shame you didn't ask on here before getting the master cylinder relined. Could have saved you a few quid.
The Chevrolet C10 pickup from the 1960s used the same master cylinder housing as the big ford's and TW's.

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I got mine a few years ago posted and taxes paid for £59, i then removed the pistons and seals and out a new seal kit in. That sorted mine so didn't have to delve into the trumpets.
If your on facebook join 'The Ford big 6 group. Plenty of hints and tips there,

 

[Lsmith80]

That's interesting to know even though I went splashing out. Thanks for the Facebook tip too.

 

[Happy hillbily]

I was in the same boat, new Holland wanted £1118 for a new master cylinder, but didn't have stock anywhere globally.
I did get a price of £80 a bore to machine and fit a stainless steel sleve to the master cylinder. But then a nice chap messaged me and told me about the hack.

The Big Ford 6 Cylinder Tractor Register | Facebook

The Big Ford Tractor Register was set up by myself Andrew Collier in May 2009 following many people contacting me regarding Ford TW, 30,40 and 70 series Tractors. We currently have over 100 members...

www.facebook.com

 

[Lsmith80]

The Big Ford 6 cylder tractor register, looks good, so I just requested to join.
£1118 for the new genuine part sounds very believable. I sometimes wonder what the total bill would be if the whole machine was bought in the form of its most elementary parts.